A Nomogram for Predicting the Renal Dysfunction Based on an 8 Years Follow Up Study in a Chinese Population Reducing Exposed to Cadmium

Objective: Cadmium exposure is associated with renal dysfunction. However, the outcome of renal function in subjects with reduction in cadmium exposure for years has not completely clarified, in particular for individuals with normal baseline renal function. In this study, we used nomogram model to predict the renal dysfunction after reduction of cadmium exposure in those subjects with normal baseline renal function. Methods: In 1998, a survey was performed in 790 subjects living in control and cadmium polluted areas. 497 subjects was followed up in 2006. 373-407 subjects with normal renal function were included in this analysis. The cadmium in blood (BCd) and urine (UCd) were detected using flame atomic absorption spectrometry. The differences in BCd, UCd, UBMG, UNAG and UALB between 1998 and 2006 were analyzed. Logistic regression model was used to identify the potential predicting factors for renal function at follow-up. Nomogams were developed based on those predictive factors. Bootstrap self-sampling, calibration curves and Receiver Operating Characteristic curves (ROC) were performed to quantify our modeling strategy. Results: The BCd levels were significant decreased (differences: 3.42 - 3.45 μg/L) and renal biomarker were increased at the follow-up compared to those at baseline. UCd levels were also decreased (0.20 - 0.52 μg/g creatinine), but no significant differences were found. Significant increases were observed in urinary β2Microglobulin (UBMG), urinary Nacetyl-β d-glucosaminidase (UNAG) and urinary albumin (UALB) in 2006. Baseline age, gender, BCd and UNAG or UBMG or UALB were used to construct the nomogam. The internal validation showed the C-index was 0.70-0.74 in predicting renal dysfunction. The area under the curve of the nomogram was 0.70 - 0.74. Decision curve analysis verified the predictive value of nomogram. Conclusion: Nomogram may be a potential risk assessment tool for predicting the progress of renal function in a cadmium-exposed population with normal baseline kidney function. Funding Statement: This study was funded by National Natural Science foundation of China (No. 81773460, 81102148) and the European Union (Sixth Framework Programme; PHIME; FOOD-CT-2006-016253). Declaration of Interests: The authors stated: None. Ethics Approval Statement: The study was approved by Institutional Review Board of Fudan University (Shanghai, China). During the study, Declaration of Helsinki was followed. Informed consent was obtained from each participant.